Analysis of interaction between dental structural protein and adhesive component substances by circular dichroism measurement

本研究课题“通过圆二色性测量分析牙体结构蛋白与牙体粘附成分物质之间的相互作用”，将圆二色性（CD）技术引入牙体研究领域，从分子水平揭示胶原蛋白与牙体粘附相关物质之间的详细相互作用，获得了以下重要发现。1. CD测量揭示了由介质的pH变化引起的水溶性胶原蛋白的可逆的两态结构转变。在pH 3时，胶原蛋白具有类似于聚（Pro）II的构象，DSC测量显示出明显的吸热峰，这两者都表明胶原蛋白在弱酸性pH 3时不变性。虽然通过在中性pH下胶原蛋白聚集体的形成预期疏水区域的存在，但是使用芘作为疏水探针的荧光光谱实验没有证明这样的区域.醇类化合物不影响 ...更多信息 影响胶原蛋白的二级结构，但它们降低或升高胶原蛋白的结构稳定性（变性温度），这取决于它们的类型和浓度（和介质的pH值），如CD光谱和CD变性曲线所观察到的。虽然CD显示出巨大的好处，但也发现了一些局限性：所有材料都应可溶于适当的溶剂，添加剂应是光学透明的，以免干扰胶原的CD，这在牙科粘附研究中有时很困难。除了CD实验之外，还通过系统DSC测量建立了添加剂的“稳定化指数”，其是添加剂使胶原螺旋稳定或不稳定的强度的量度。添加剂越疏水（即，比介电常数越小），其越有效地降低胶原的结构稳定性。这一指标对于预测某些新型牙科材料与牙本质胶原之间的相互作用具有重要意义。少

In this project entitled "Analysis of interaction between dental structural protein and adhesive component substances by circular dichroism measurement," a circular dichroism (CD) technique was introduced to the dental research field to reveal the detailed interaction between collagen and dental-adhesive-related substances at a molecular level, and several important findings have been obtained as follows.1. CD measurements revealed a reversible two-state structural transition of a water-soluble collagen caused by pH change of the media. At pH 3, the collagen had a conformation similar to poly(Pro)II and a DSC measurement showed a distinct endothermic peak, both indicating that the collagen was not denatured at a weakly acid pH of 3. Though an existence of hydrophobic region was expected by the formation of aggregates of the collagen at a neutral pH, no such region was proven by a fluorescence spectroscopy experiments using pyrene as a hydrophobic probe.2. Alcoholic compounds did not af … More fect the secondary structure of the collagen, but they either lowered or raised the structural stability (denaturation temperature) of the collagen depending on their types and concentrations (and pH of the media), as observed by CD spectra and CD denaturation curves. While the great benefit of CD was shown, some limitations were also found : all materials should be soluble in appropriate solvents and the additives should be optically transparent so as not to interfere with the CD of the collagen, which are sometimes difficult in a dental adhesion research.3. In addition to the CD experiments, a "stabilization index" of the additives has been built up by systemic DSC measurements, which is a measure of how strongly an additive stabilizes or destabilizes the collagen helix. The more hydrophobic the additive is (i.e., the smaller the specific dielectric constant is), the more effectively it lowers the structural stability of collagen. This index must valuably serve to foresee the interaction between some newly developed dental materials and dentinal collagen. Less